The present invention is related to gauge pointers. More specifically, the present invention is related to an apparatus for accurately determining the indicating position of a gauge.
In traditional gauge pointer applications, the pointer is driven against a fixed pointer stop upon activation of a system. Using this application, a known position of the pointer can be determined and used for reference when the system is active. A disadvantage of this technique is that an undesirable audible noise is generated when a stepper motor rapidly steps the pointer against the stop.
Other traditional gauge applications do not have a fixed pointer stop. These applications usually have a pointer with a circular rotation of 360 degrees or greater. Driving signals that operate the pointer position may cause an undesirable situation when the position may not be accurately known after a period of time. The cause of this situation may be the result of extreme accelerations, vibration, and drift over time of electronic components. A solution to this problem is the zeroing of the pointer, which is the forcing of mechanical and electrical alignment of the pointer. Traditional zeroing techniques require the use of complex internal optics to detect gear alignment of a pointer motor.
It is the objective of the present invention to overcome these and other fallbacks and complexities in the prior art by providing an apparatus for accurately determining and correcting the indicating position of a pointer.
The present invention is an apparatus for accurately sensing the absolute position of a gauge. The apparatus includes at least one pointer having a predefined rotation with a circular travel pattern. The apparatus also includes at least one light emitting diode that generates an optical signal. The apparatus also includes at least one optical sensor placed in a fixed position along the circular travel pattern of the pointer. The apparatus also includes a pointer driver that drives the pointer.
The present invention is also directed to a method for detecting and correcting the indicating position of a pointer. The method comprises the steps of generating an optical signal from the light emitting diode, transmitting an optical signal through the pointer hub, sensing an optical signal at the sensor, calculating an error between an actual sensed position of the pointer and a former assumed position of the pointer, zeroing the stepper motor from the calculated error, and transmitting a stepper signal to the pointer driver.